This field guide is nearly twenty years old, but there are so few field guides to fungi that it still remains a standard reference. Like all Peterson field guides, it is handy and compact and can easily be taken into the field and pored over with the mushrooms in their wild habitat. The text is detailed and accurate and a "similar species" section is very useful. However, this guide uses painted plates whereas amateurs generally find it easier to identify fungi by photographs. I personally find photographs more accurate, but enjoy paintings in their own right. In this case the paintings are pleasing and quite faithful.
Although this guide should be on every mushroom enthusiast's shelves, a better beginners guide might be Roger Phillips' photographic book which has now appeared in a revised edition (on Amazon.com: ISBN 1554071151). Phillips provides 1000 photographs compared to this guide's 700 illustrations. However, Phillips is rather large to take into the field except in a backpack. Bear in mind that no fungus guide is comprehensive - each treats a selection of species - so it is wise to have a good selection in order to be in with a chance of correct identification.
So, until a compact photographic guide to fungi appears, this tried and tested Peterson guide will continue to fill a niche in the mushroom hunter's library.